1. Field of the Invention
The present invention generally relates to the field of digital video broadcasting and, more particularly, to a method and related controlling apparatus for filtering the SDTV channels in a digital video broadcasting.
2. The Related Art
As the constant improvement in technologies, people have an increasing demand on higher quality of TV broadcasting. Digital video broadcasting (DVB), providing better quality of audiovisual programs, are gaining attentions in recent years.
The USB ports of personal computers (PCs) can be used to connect many universal serial bus (USB) peripherals, including USB keyboard, USB mouse, USB card reader, USB flash drive, external USB hard disk, USB printer, and USB scanner. The USB ports provide convenience to the users. The transmission speed of USB has also evolved from the 12 Mbps of USB1.1 to the recent 480 Mbps of USB2.0.
According to the transmission specification of USB, the USB1.1 can support low speed peripherals, such as USB keyboard, USB mouse, and USB joy stick, whose transmission speed is 1.5 Mbps with the tolerance of 1.5%, and the full speed peripherals, such as USB flash drive, USB printer, and USB scanner, whose transmission speed is 12 Mbps with a tolerance of 0.25%. On the other hand, USB2.0 is capable of supporting high-speed peripherals, whose transmission speed is as high as 480 Mbps. USB2.0 is downward compatible with the USB1.1, and therefore, USB2.0 can support low speed, full speed and high-speed peripherals.
FIG. 1 of the attached drawings shows a schematic view of a typical USB DVB reception device, including an antenna 100, a tuner 110, a demodulator 120, and a USB controller 130. The DVB signal, including video signal, audio signal and control packets, transmitted through air enters antenna 100. The DVB reception device uses tuner 110 to receive RF signals, uses demodulator to demodulate the RF signals, and sends an MPEG2 video signal to USB controller 130 for using its USB2.0 high-speed interface to communicate with the host.
FIG. 2 shows a transmission packet 200 of the DVB. Each packet is 188 bytes long, including a program ID (PID) for indicating the type of the packet.